• Journal of the Korean Magnetics Society
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• v.3 no.3
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• pp.208-214
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• 1993

In order to investigate the origin of an increase in the coercivity with the Ta addition to Co-Cr films, the perpendicular magnetic anisotropy of Co-Cr film and CoCrTa film was measured by a torque magnetometer and VSM. In Co-Cr binary alloy film, the uniaxial anisotropy increased with increasing Cr content. The perpendicular magnetic anisotropy of $Co_{81.7}Cr_{16.7}Ta_{1.6}$ film was larger than that of $Co_{81}Cr_{19}$ film, both of which were deposited at the same substrate temperature of $100^{\circ}C$. The change in the perpendicular magnetic anisotropy with annealing was studied to understand the Ta addition effect. The amount of decrease in perpendicular magnetic anisotropy of the CoCrTa film by the annealing was larger than that of Co-Cr film. And the perpendicular magnetic anisotripies of Co-Cr film and CoCrTa film after annealing were almost the same. The cause of this was interpretated as the enhanced segregation of solute atoms in the Ta added thin film in the as-deposited state. The enhanced segregation of solute atoms increases the perpendicular magnetic anisotropy of the film, and causes the increase of perpendicular coercivity of the film.

• Journal of the Korean Magnetics Society
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• v.9 no.4
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• pp.203-209
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• 1999

Effects of Mo and Si addition in Cr underlayer on magnetic properties of CoCrTa/CrMo and CoCrTa/Si thin films media were investigated. Thin films were prepared with DC magnetron sputtering system. The thickness of CoCrTa magnetic layer and Cr underlayer were fixed at 300 $\AA$ and 700 $\AA$, respectively. The substrate heating temperature was kept constant at 26$0^{\circ}C$ for both magnetic layer and underlayer preparation. The coercivity increase of CoCrTa film was realized due to Mo addition in Cr underlayer. Si addition made a small decrease in coercivity. Coercivity increase seems to be attributed by the improvement of preferred orientation of Cr(200) plane. It is found that lattice fit between Cr(200) and CoCrTa(1120) of CrMo underlayer is better than that of CrSi underlayer. This small misfit may also contribute coercivity increase.

• Journal of the Korean Magnetics Society
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• v.3 no.4
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• pp.314-319
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• 1993

The Effects of additional element X (X = Si, Mo, Cu, Gd) on magnetic properties and microstructure of Co-1Zat%Cr-Zat%Ta/Cr-X magnetic thin film were investigated. The thickness changes of Cr-X underlayer and CoCrTa magnetic layer were in the range of $1000~2000\AA$ and $200~800\AA$. respectively. Substrate temperatures were controlled from $100^{\circ}C$ to $200^{\circ}C$. Increase of coercivity by about 100~200 Oe was observed in CoCrTa/Cr-X thin films compared to those without additional X element. Cu was the most effective additional element for increasing coercivity. CoCrTa/Cr-Cu thin film shows relatively high coercivity in $1500\AA$ underlayer thickness and $600\AA$ magnetic layer thickness.

• Journal of the Korean Magnetics Society
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• v.3 no.1
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• pp.41-47
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• 1993

Effects of Ta addition on Co-Cr pependicular magnetic recording media were studied to obtain high perpen-dicular coercivity at lower substrate temperature. For the purpose. magnetic properties and microstructures of Co-Cr-(Ta) films were studied by varying the Cr contents from 17 to 21 at.% and Ta contents for 0 to 3.2 at.%. Effectiveness of Ta addition in increasing perpendicular coercivity was significant for lower Cr content films. The increasement of perpendicular coercivity was more pronounced for the films deposited on $100^{\circ}C$ heated substrate in the case of ${(Co_{83}Cr_{17})}_{98.4}Ta_{1.6}$ composition. The cause of the increase of perpendicular coercivity was considered due to not the grain refinement effects and the improvement of c-axis alignments but increase of Ta and Cr segregation.

• Proceedings of the Korean Magnestics Society Conference
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• 1995.05a
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• pp.86-87
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• 1995

• Journal of the Korean Magnetics Society
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• v.9 no.4
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• pp.210-216
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• 1999

The objective of this paper is to investigate corrosion behaviors of CoCrTa/CrNi thin film and post heat-treatment effect. An electron beam evaporator was used for films deposition. After evaporation, post heat-treatment was carried out under $5.0{\times}10^3$ Torr vacuum condition. Annealing temperature and time were 400 $^{\circ}C$ and 30 min, respectively. To understand the effect of annealing on corrosion behavior of CoCrTa/CrNi, potentiodynamic polarization technique and accelerated corrosion chamber test were undertaken. Corrosion potential is higher for the annealed samples (CoCrTa 400$\AA$/CrNi 1000$\AA$) than for as-deposited one. This is attributed to an enrichment of Cr in the surface layer of the thinfilm resulting in a more corrosion resistant material.

• Proceedings of the Korean Magnestics Society Conference
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• 1996.05a
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• pp.48-49
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• 1996

• Proceedings of the Korean Magnestics Society Conference
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• 1995.10a
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• pp.94-95
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• 1995

• Proceedings of the Korean Magnestics Society Conference
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• 1991.11a
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• pp.102-103
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• 1991

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.578-581
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• 1999

The Co-Cr-Ta films are one of the most suitable candidates for perpendicular magnetic recording media. The facing targets sputtering(FTS) system has a advantage of preparing films over a wide range of working gas pressure on plasma-free substrates. In this study, we investigated the effect underlayers on the growths layers of Co-Cr-Ta recording layers. The Co-Cr-Ta/Ti(CoCr) double layers were deposited with sputter gas pressure$(P_N, 0.3-1mTorr)$ by using FTS apparatus at temperature of$40^{\circ}C~-300^{\circ}C$, respectively. Crystallographic and magnetic characteristics were evaluated by x-ray diffractometry(XRD) and vibrating sample magnetometer(VSM), respectively.